1. Field of the Invention
The present invention relates to aerobic fermentation promoting device, aerobic fermention system using this device and natural fermentation compost fertilizer made from livestock excrements including human excrements and, more particularly, to a movable device for promoting aerobic fermentation device of compost raw materials comprised of the mixture of excrements and the moisture contents control materials, for example, rice hulls, sawdust, wood pieces, leaves and trunks of plants, and to an aerobic fermentation system equipped with such a fermentation promoting device, and to high quality composts fertilizer produced through this fermentation system which completely extinct various pathogenic factors like bacteria,fungi and others including vermin eggs and noxious plant seeds.
2. Description of the Prior Art
In order to make highly good nature compost fertilizer from the livestock excrements including human excrements, the aerobic fermentation process at high temperature more than 60.degree. C. has been widely used. There are two fermentation types, first the aerobic fermentation requiring oxygen during fermentation of the compost raw materials and second the anaerobic fermentation requiring no oxygen during fermentation of the compost raw materials. However, the anaerobic fermentation process is not acceptable for the fermentation process of the organic materials because quite a lot of nourishment loss, much generation of noxious organic acid gas, unexpected propagation of pathogenic factors and many other side results happens during factors and many other side results happens during fermentation.The aerobic fermentation at a relatively high temperature of at least 60.degree. C. supplying appropriate amount of oxygen is recommended to overcome the bad results happened during the anaerobic fermentation process. Well-seasoned compost prepared through the aerobic fermentation process provides excellent vegetation environment conditions good for the plants.
In the prior art, there have been proposed air supply devices for compost raw materials, aiming at the above-mention point, as disclosed in U.S. Pat. No. 441,039. In the above U.S. patent, a longitudinal air supply tube is deeply inserted into compost raw material heap to supply the outside fresh air into the compost raw material heap. However, the said air supply device can not work effectively to let the fresh outside air supplied to the compost raw material heap to be uniformly distributed to all of the compost raw material enough to prevent the propagation of pathogenic factors but merely supply the fresh air just around the air outlet section of the air supply tube inserted in the compost raw material heap.
There has been proposed a fermentation system in that the compost raw materials, such as human excrement, animal excrement and the sawdust, are put in a large-sized fermentation tank capable of containing compost raw materials from several ten tons to several hundred tons. A large-sized mixer integrated with a slowly movable conveyor system is installed in the fermentation tank to mix the compost raw materials in the tank and achieve smooth fermentation of the compost raw materials. However, the said fermentation system needs a large-sized steel structure installed on the fermentation tank, the large-sized mixer device for mixing many hundred tons of the compost raw materials and a drive unit for driving the mixer device. In this regard, this fermentation system has been scarcely used in small-scaled stock farms due to its large size. The said fermentation system has another problem that it can not achieve uniform mixing ability of the raw materials and cause anaerobic fermentation partialy further to lead the additional mixing process using an agricultural power shovel.
There have been also a continuous fermentation process using silos. This process, a continuous fermentation method, has a problem of consuming too much cost constructing large scale installation of the silos so that this continuous fermentation process also was not used except large scale livestock farms. Another problem of the above continuous fermentation is that the continuous fermentation can not achieve uniform mixing of the compost raw materials and, as a result, scarcely achieves the full scale aerobic fermentation of the compost materials.